Lubricating nipples are available in different embodiments. Lubricating nipples frequently include a thread that is threaded into a threaded bore or turned into a bore without a thread in a self-cutting way. For cost-cutting purposes, lubrication nipples are frequently pressed or beaten into the bores and positioned in the bore via a press-fit. Such pressed lubricating nipples are known from EP 0 450 845 B1. Here, a multi-head lubricating nipple assembly is provided with a plurality of lubricating nipples. Each lubricating nipple is pressed into a corresponding bore of a basic member. U.S. Pat. No. 2,250,123 also shows lubricating nipples that are pressed into bores wherein, inter alia, there is shown a press fit in a bore of a thin-walled component.
The lubricating nipples that are pressed in or beaten in the bores are disadvantageous in that the holding forces of the lubricating nipples depend entirely on the fitting conditions of the press fit. Thus, relatively low extraction forces, such as centrifugal forces or vibrations of the lubricating nipple, are sufficient to remove the lubricating nipple from the bore arranged in the base of the bearing bushes of a universal joint.
In the case where high forces are generated, such as in universal joints as a result of centrifugal forces, there is a need for particularly high holding forces. This requires high pressing-in forces during assembly. In addition, because of the thin walls of the bearing bushes of the universal joints, it is difficult to achieve a sufficiently high production accuracy that ensures sufficiently small deviations of the holding force after assembly.